2 files changed, 3 insertions, 2 deletions
diff --git a/Makefile b/Makefile
index 23ff090..a107318 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@ CC=cc
 PREFIX=/usr/local
 SYSCONFDIR=/etc
 CFLAGS=-std=c99 -Werror -D_XOPEN_SOURCE=700 -D_GNU_SOURCE -D_POSIX_C_SOURCE=200809L
-CWARN=-Wall -Wpedantic -Wextra -Wsign-conversion -Wtype-limits -Wunused-result
+CWARN=-Wall -Wpedantic -Wextra -Wsign-conversion -Wtype-limits -Wunused-result -Wnull-dereference
 EXTRA=
 G=
 O=-O3
diff --git a/match.c b/match.c
index 19cb14d..25a08a7 100644
--- a/match.c
+++ b/match.c
@@ -52,9 +52,10 @@ static match_t *match(def_t *defs, file_t *f, const char *str, pat_t *pat, bool
 // If the given pattern is a reference, look it up and return the referenced
 // pattern. This is used for an optimization to avoid repeated lookups.
 //
+__attribute__((nonnull, returns_nonnull))
 static inline pat_t *deref(def_t *defs, pat_t *pat)
 {
-    if (pat && pat->type == BP_REF) {
+    if (pat->type == BP_REF) {
         def_t *def = lookup(defs, pat->args.ref.len, pat->args.ref.name);
         if (def) pat = def->pat;
     }